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From:   Song Liu <liu.song.a23@gmail.com>
Date:   Mon, 28 Jan 2019 23:07:54 -0800
Message-ID: <CAPhsuW6zCrQ5wn+PG4B3KWqEmMsVPEuJGy24GCUYdCH=t9VpKg@mail.gmail.com>
Subject: Re: [PATCH] include/linux/bpf.h - fix missing prototype warnings...
To:     Valdis Kletnieks <valdis.kletnieks@vt.edu>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Networking <netdev@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
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On Mon, Jan 28, 2019 at 10:05 PM <valdis.kletnieks@vt.edu> wrote:
>
> Compiling with W=1 generates warnings:
>
>   CC      kernel/bpf/core.o
> kernel/bpf/core.c:721:12: warning: no previous prototype for ?bpf_jit_alloc_exec_limit? [-Wmissing-prototypes]
>   721 | u64 __weak bpf_jit_alloc_exec_limit(void)
>       |            ^~~~~~~~~~~~~~~~~~~~~~~~
> kernel/bpf/core.c:757:14: warning: no previous prototype for ?bpf_jit_alloc_exec? [-Wmissing-prototypes]
>   757 | void *__weak bpf_jit_alloc_exec(unsigned long size)
>       |              ^~~~~~~~~~~~~~~~~~
> kernel/bpf/core.c:762:13: warning: no previous prototype for ?bpf_jit_free_exec? [-Wmissing-prototypes]
>   762 | void __weak bpf_jit_free_exec(void *addr)
>       |             ^~~~~~~~~~~~~~~~~
>
> All three are weak functions that archs can override, although none do so
> currently.  Provide prototypes for when a new arch provides its own.
>
> Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>

Acked-by: Song Liu <songliubraving@fb.com>

>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 3851529062ec..99e55313123f 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -472,6 +472,10 @@ _out:                                                      \
>  #define BPF_PROG_RUN_ARRAY_CHECK(array, ctx, func)     \
>         __BPF_PROG_RUN_ARRAY(array, ctx, func, true)
>
> +u64 __weak bpf_jit_alloc_exec_limit(void);
> +void *__weak bpf_jit_alloc_exec(unsigned long size);
> +void __weak bpf_jit_free_exec(void *addr);
> +
>  #ifdef CONFIG_BPF_SYSCALL
>  DECLARE_PER_CPU(int, bpf_prog_active);
>
>